JP2011005757A - Head unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress the heat deformation of a head unit.SOLUTION: The head unit 7 includes: a frame 70 of rectangular shape; recording heads 76 which are arranged at the bottom of the frame 70 and in which nozzles 760 for discharging an ink droplet are arranged, and an instrument-installed equipment which is arranged in the frame 70 and makes the ink droplet discharged from the nozzles 760. In the side pole part 71a of side plates 71, 71 of the frame 70, a rib 711a extending in the vertical setting direction of the side pole part 71a is formed, and a channel 713 for making a cooling medium circulated is formed. The rib 711a composes the channel wall of the channel 713.

Description

  The present invention relates to a head unit.

  2. Description of the Related Art Conventionally, as an ink jet recording apparatus that records a desired image by ejecting ink droplets from an ink jet head to a recording medium, an apparatus that performs image recording while scanning a head unit equipped with the ink jet head in a predetermined direction is known. (For example, refer to Patent Document 1).

  The head unit is equipped with an actuator for discharging ink droplets from a plurality of nozzles of an inkjet head, and electrical equipment such as a drive substrate. Since these electrical devices generate heat during image recording, the frame of the head unit is thermally deformed to reduce the ink droplet ejection accuracy, and consequently the image quality.

  As a method of suppressing such thermal deformation, if the rigidity of the frame of the head unit is simply increased, the weight of the head unit increases, making handling difficult or reducing the scanning speed. Further, when the electrical equipment is air-cooled, the head unit is swung by the cooling air, and the ink droplet ejection accuracy is lowered.

  Therefore, there has been a demand for a technique capable of effectively suppressing thermal deformation without accompanying an excessive weight increase of the head unit and a decrease in ejection accuracy.

JP 2008-225248 A

  The subject of this invention is providing the head unit which can suppress a thermal deformation effectively.

In order to solve the above-mentioned problem, the invention according to claim 1
A rectangular frame;
At least one inkjet head disposed at the bottom of the frame and having a plurality of nozzles for discharging ink droplets;
An electrical device disposed on the frame for discharging ink droplets from the plurality of nozzles;
In a head unit comprising:
On the side column of the frame body, ribs extending in the standing direction of the side column are formed, and a flow path for circulating the refrigerant is formed.
The rib constitutes a flow path wall of the flow path.

The invention according to claim 2 is the head unit according to claim 1,
The plurality of nozzles are arranged in a left-right direction of the frame,
The rib is erected toward the outside of the frame body along the left-right direction of the frame body.

  According to the present invention, the side pillar of the frame is formed with the rib extending in the standing direction of the side pillar, and the flow path for circulating the refrigerant is formed. Since the wall is formed, the rigidity of the side pillar is enhanced by the rib, and the side pillar is cooled by flowing the coolant through the flow path that forms the flow path wall. As a result, the rib shape is set to the minimum height and thickness necessary for flow path formation, and the side column is highly rigid while suppressing an increase in the weight of the head unit, and the head unit is cooled by cooling air. Heat generation from the electrical equipment can be removed without causing oscillation. Therefore, thermal deformation can be effectively suppressed without accompanying an excessive increase in the weight of the head unit or a decrease in ejection accuracy.

It is a perspective view of an inkjet recording device. It is the perspective view which looked at the head unit from the upper front side. It is a fragmentary sectional view of the side plate of a head unit. It is the perspective view which looked at the head unit from the lower part of the back side.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of an inkjet recording apparatus 1 including a head unit 7 according to the present invention.
As shown in this figure, the ink jet recording apparatus 1 includes a bottom plate 2 and a support base 3 disposed on the bottom plate 2. The ink jet recording apparatus 1 records a desired image by ejecting ink droplets onto a recording medium.

  On the bottom plate 2, a platen 21 that supports a recording medium (not shown) from the non-recording surface side and a maintenance unit 22 that performs maintenance of recording heads 76, which will be described later, are in the direction of arrow Y in the figure (hereinafter referred to as sub-scanning). In the direction Y). Among these, the platen 21 can be moved in two directions of an arrow X perpendicular to the sub-scanning direction Y (hereinafter referred to as a main scanning direction X) and a sub-scanning direction Y by a platen moving mechanism (not shown). , Rotation in the XY plane (horizontal plane) is possible.

  The support 3 is a gate-shaped support that is disposed so as to extend in the sub-scanning direction Y across the platen 21 and the maintenance unit 22, and is formed of a stone material in the present embodiment. Further, the carriage 3 is supported on the support table 3 in a gantry structure so that the carriage 5 can move in the sub-scanning direction Y.

  The carriage 5 includes a substantially casing-shaped carriage main body 51 and a projecting portion 52 projecting from the carriage main body 51 in the main scanning direction X. The protruding portion 52 is supported by the carriage body 51 via a head lifting mechanism (not shown), and can be moved in the vertical direction Z with respect to the carriage body 51 by this head lifting mechanism. The head unit 7 is suspended from the tip of the protruding portion 52.

FIG. 2 is a perspective view of the head unit 7.
As shown in this figure, the head unit 7 includes a substantially rectangular frame 70. The frame body 70 is mainly composed of two side plates 71, 71, a top plate 72, and a head plate 73 forming a bottom plate.

  Of these, the side plates 71, 71 support the head unit 7 at both ends of the head unit 7 in the sub-scanning direction Y. The side plate 71 includes a side plate main body 711 fixed to the top plate 72 and the head plate 73, and a lid plate 712 attached to a side portion of the side plate main body 711. The side plate main body 711 and the cover plate 712 are largely removed at the upper and lower portions, except for the outer edge, mainly for weight reduction. As a result, the front and rear side column portions 71a and 71a are arranged at the upper and lower ends and the middle step. The three beam portions 71b to 71d are connected to each other.

  Among the side plates 71, the side plate main body 711 is formed with ribs 711 a along the entire edges thereof. More specifically, the side column portion 71a of the side plate main body 711 is formed with ribs 711a extending in the standing direction of the side column portion 71a, that is, the vertical direction Z, along the edges thereof, and the beam portions 71b to 71d. The ribs 711a extending in the extending direction of the beam portions 71b to 71d, that is, the main scanning direction X are formed along the edges. The ribs 711 a are erected toward the outside of the frame body 70 along the left-right direction of the frame body 70, that is, along the sub-scanning direction Y. The ribs 711a are also formed to extend in the main scanning direction X at the positions of the upper ends of the lower beam portion 71c and the middle beam portion 71d in the side column portions 71a and 71a of the side plate body 711. ing.

  Of the side plate 71, the cover plate 712 is fixed over the entire top surface of the rib 711 a of the side plate main body 711. Thereby, between the side plate main body 711 and the cover plate 712, the flow path 713 as shown in FIG. 3 is formed over the whole surface of the side column part 71a and the beam parts 71b-71d. At this time, the rib 711a forms a flow path wall of the flow path 713. Further, as shown in FIG. 2, the lid plate 712 has holes 712a formed in the side column portions 71a and 71a slightly above the middle beam portion 71d, and slightly above the lower beam portion 71c. Holes 712b are formed in the side column portions 71a and 71a, and hole portions 712c are formed at both ends of the lower beam portion 71c.

  A substrate mounting plate 74 is provided at a middle height of the side plates 71, 71, and a substrate box 75 is fixed on the substrate mounting plate 74. In the substrate box 75, there are a drive board (not shown) for controlling the ejection of ink droplets from nozzles 760,... Described later, an electromagnetic valve (not shown) for distributing ink to the nozzles 760,. The refrigerant | coolant pump which is not illustrated for distribute | circulating a refrigerant | coolant to the flow path 713 of the side plates 71 and 71 is accommodated. The refrigerant pump communicates with the holes 712a to 712c of the lid plates 712 of the side plates 71 and 71 via a refrigerant tube (not shown).

  The top plate 72 is suspended from the projecting portion 52 of the carriage 5 via a head rotation mechanism 721 provided on the top surface thereof. With the head rotating mechanism 721, the head unit 7 can rotate in the XY plane with respect to the protruding portion 52.

FIG. 4 is a perspective view of the head unit 7 as viewed from below on the rear side (back side in FIG. 1).
On the lower surface of the head plate 73, a plurality of recording heads 76 arranged in the sub-scanning direction Y for each column are provided in two rows in the main scanning direction X so as to have a staggered arrangement.

  The recording heads 76,... Are ink jet heads according to the present invention, and the recording heads 76,... Have a plurality of nozzles 760,. It is arranged. The recording heads 76 are connected to a drive substrate in the substrate box 75 and communicated with an ink tank via an electromagnetic valve. The nozzles 760,... Are provided with piezoelectric elements (not shown) that are deformed by the application of voltage, and the nozzles 760,. It is comprised so that may be discharged. More specifically, when a driving voltage is applied to the piezoelectric elements, the nozzles 760,... Are deformed to compress an ink flow path (not shown) inside the nozzles 760,. It is designed to be ejected as drops. In addition, although a well-known material can be used as a piezoelectric element material, lead zirconate titanate (PZT) is particularly preferable.

  Further, two cameras 77 and 77 capable of photographing the lower part are disposed on the rear surface side (front side in FIG. 4) of the head unit 7. The two cameras 77 and 77 are for confirming and adjusting the ejection position of the ink droplets, and are used for fine adjustment and coarse adjustment, respectively, and have different telephoto magnifications.

  In the head unit 7 having the above-described configuration, electrical devices such as a piezoelectric element, a drive substrate, and an electromagnetic valve for discharging ink droplets from the nozzles 760,. This heat generation may cause the frame body 70 to be thermally deformed and cause a drop in ink droplet ejection accuracy from the nozzles 760,. In particular, thermal deformation of the side column portions 71a of the side plates 71, 71, particularly thermal deformation in the main scanning direction X perpendicular to the arrangement direction of the recording heads 76,. This is because the deformation in the sub-scanning direction Y may be absorbed by the piezoelectric element that drives the nozzles 760,.

  In response to such thermal deformation of the frame 70, the head unit 7 circulates a refrigerant such as air or water through the refrigerant tube from the refrigerant pump to the flow path 713 of the side plates 71 and 71 during image recording. More specifically, the coolant is caused to flow into the flow path 713 including the upper side column portions 71a and 71a and the upper end beam portion 71b via the holes 712a and 712a, and the lower side column is determined via the holes 712b and 712b. The refrigerant is caused to flow through the flow path 713 including the portions 71a and 71a and the middle beam portion 71d, and the refrigerant is allowed to flow through the hole portions 712c and 712c into the flow path 713 including the lower beam portion 71c. As a result, the side plates 71 and 71 are cooled to suppress thermal deformation thereof, in particular, thermal deformation of the side column portion 71a, thereby preventing a drop in ink droplet ejection accuracy. At the same time, the rib 711a constituting the flow path wall of the flow path 713 increases the rigidity of the side column portion 71a, further suppresses deformation of the side column portion 71a, and more reliably prevents the ink droplet ejection accuracy from being lowered. Can do.

  As described above, according to the head unit 7, the side column portion 71a of the side plate main body 711 of the frame body 70 is provided with the rib 711a extending in the standing direction of the side column portion 71a, and the refrigerant. The rib 711a constitutes the flow path wall of the flow path 713, and the rib 711a increases the rigidity of the side column portion 71a, and the rib 711a forms the flow path wall. The side column portion 71 a is cooled by flowing the coolant through the flow path 713. As a result, the ribs 711a have the minimum height and thickness necessary for flow path formation, and the side column 71a is made highly rigid while suppressing an increase in the weight of the head unit 7, and the cooling air is cooled by water cooling. The heat generation of the electrical equipment can be removed without causing the head unit 7 to oscillate. Therefore, thermal deformation can be effectively suppressed without accompanying an excessive increase in the weight of the head unit 7 or a decrease in ejection accuracy.

  It should be noted that the present invention should not be construed as being limited to the above-described embodiment, and of course can be modified or improved as appropriate.

  For example, in the above embodiment, a plurality of recording heads 76 are mounted on the head unit 7, but it is sufficient that at least one recording head 76 is mounted. However, the above-described decrease in ejection accuracy due to thermal deformation of the frame body 70 is greater when the head unit formed in the sub-scanning direction Y is deformed by twisting the head unit. Therefore, the effect of suppressing thermal deformation in the head unit 7 in the present embodiment is particularly significant in the head unit 7 on which a plurality of recording heads 76 are mounted.

  In addition, although the piezoelectric element, the drive substrate, and the electromagnetic valve mounted on the head unit 7 are cited as the heat source that thermally deforms the frame 70, the cameras 77 and 77 can also serve as the heat source. Further, the drive motor for the head rotation mechanism 721 provided in the projecting portion 52 of the carriage 5 also transmits heat to the head unit 7 through the head rotation mechanism 721, so that the frame body 70 is similarly thermally deformed. Can be a heat source.

  The head unit 7 has been described as effectively suppressing thermal deformation. However, the ribs 711a increase the rigidity of the side plates 71, 71, and the side plates 71, 71 are cooled to increase the temperature. Since the strength reduction of 71 is prevented, it is of course effective for deformation other than thermal deformation such as deformation due to external force or temporal deformation.

7 Head Unit 70 Frame 71 Side Plate 71a Side Column (Side Column)
76 Recording head (inkjet head)
711a Rib 713 Flow path 760 Nozzle Z Vertical direction (side column standing direction)

Claims (2)

A rectangular frame;
At least one inkjet head disposed at the bottom of the frame and having a plurality of nozzles for discharging ink droplets;
An electrical device disposed on the frame for discharging ink droplets from the plurality of nozzles;
In a head unit comprising:
On the side column of the frame body, ribs extending in the standing direction of the side column are formed, and a flow path for circulating the refrigerant is formed.
2. The head unit according to claim 1, wherein the rib constitutes a channel wall of the channel. The plurality of nozzles are arranged in a left-right direction of the frame,
The head unit according to claim 1, wherein the rib is erected toward the outside of the frame body along a left-right direction of the frame body.

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